A number of peroxo compound activators are known. The most common of these is tetracetylglycoluril, as disclosed in West German Pat. No. 1,770,854. Tetracetylglycoluril is an efficient and potent activator and has become a reference standard in the industry for the evaluation of other peroxo activators. Other known activators are tetracetylethylene diamene (West German Pat. No. 2,816,174); pentacetylglucose (Japanese Pat. No. 8,021,467); and N-acetylsuccinimide, N-benzoylsuccinimide, and N-acetylphthalimide (U.S. Pat. No. 3,969,257). These are all prepared by acetylation of corresponding precursors in an acetanhydride excess. Other known activators are produced on a large scale by oxidation of benzene or naphthalene in air or oxygen. These include anhydrides of organic acids such as maleinic anhydride and phthalic anhydride.
The known anhydrides suffer from a serious disadvantage when combined with a detergent or washing agent: they decompose very rapidly and loose much if not all of their activity during storage. A slower rate of decomposition has been achieved with the known acetyl compounds.
To counteract this disadvantage, researchers have sought to stabilize the activators, and a number of stabilization processes are now known. For example, the activators can be granulated and mixed with other additives, or they can be coated with a protective film. In practice, stabilization has become necessary in order to maintain the shelf-life of the known activators so that they remain effective for a reasonable period of time.
As shown in Table 1, tetracetylglycoluril is the most stable and effective of the known activators. It is also the most expensive, and is not often used for commercial applications. The table also shows that tetracetylglycoluril, tetracetylethylene diamene, and pentacetylglucose have a satisfactory shelf-life and an acceptable stability when stored with a detergent, but they are also expensive. Phthalic anhydride and N-acetylphthalimide do not have an acceptable shelf-life.